Return true from IsElementInInvisibleSubTree if root element is not rendered

This can happen if the image is in a frame that is itself invisible,
due to for example the <iframe> element owning the Frame being
display:none. In such cases the documentElement has no layout.

Bug: 1129979

Change-Id: Ic6557c936395ce539be96d255ba4f29a10b5790b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2444436Reviewed-by: Scott Little <sclittle@chromium.org>
Commit-Queue: Chris Harrelson <chrishtr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#813217}

third_party/blink/renderer/core/html/lazy_load_image_observer.cc

@@ -84,8 +84,12 @@ bool IsElementInInvisibleSubTree(const Element& element) {
     return true;
   for (Node& ancestor : FlatTreeTraversal::InclusiveAncestorsOf(element)) {
     auto* ancestor_element = DynamicTo<Element>(ancestor);
-    if (!ancestor_element)
+    if (!ancestor_element) {
+      // Return true if the whole frame is not rendered.
+      if (ancestor.IsDocumentNode() && !ancestor.GetLayoutObject())
+        return true;
       continue;
+    }
     const ComputedStyle* style = ancestor_element->EnsureComputedStyle();
     if (style && (style->Visibility() != EVisibility::kVisible ||
                   style->Display() == EDisplay::kNone)) {